Signal cable for high frequency signal transmission and method of transmission

Abstract

A signal cable, namely a coaxial cable or a balanced cable, has at least one signal conductor for transmitting high frequency signals, in particular also in the gigahertz range, while having an acceptable return loss. It is provided optionally or in combination that the signal conductor is embodied as a stranded conductor with a varying lay length or that the signal cable is a balanced cable having signal conductors that are mutually twisted with a varying lay length.

1 . A high frequency signal cable for transmitting signals at a frequency in a GHz range, comprising:
 insulated signal conductors mutually twisted in pairs being a twisted wire pair, said insulated signal conductors being mutually twisted with a varying lay length for reducing return losses; and   a shielding surrounding said twisted wire pair.   
     
     
         2 . The signal cable according to  claim 1 , wherein said lay length varies about a mean lay length by a difference value. 
     
     
         3 . The signal cable according to  claim 1 , wherein said lay length varies in a non-uniform manner. 
     
     
         4 . The signal cable according to  claim 2 , wherein said mean lay length is in a range of 3 to 50 times a diameter of an insulated signal conductor of said insulated signal conductors. 
     
     
         5 . The signal cable according to  claim 1 , wherein a variation of said lay length is characterized by an envelope that has a length in a range of a few meters. 
     
     
         6 . The signal cable according to  claim 5 , wherein the length of the envelope varies. 
     
     
         7 . The signal cable according to  claim 5 , wherein a value of a maximal lay length or a minimal lay length varies in a case of successive envelopes. 
     
     
         8 . The signal cable according to  claim 5 , wherein a gradient of the envelope varies in a case of successive envelopes. 
     
     
         9 . The signal cable according to  claim 1 , wherein said insulated signal conductors having stranded wires extending in parallel with one another with a respective identical lay length. 
     
     
         10 . The signal cable according to  claim 1 , wherein said insulated signal conductors has only one layer of stranded wires. 
     
     
         11 . The signal cable according to  claim 1 , wherein said lay length is in a range of up to 30 meters. 
     
     
         12 . The signal cable according to  claim 1 , further comprising:
 a feeder device connected to said insulated signal conductors, said feeder device embodied such that an original signal that is to be transmitted is fed into a first of said insulated signal conductors and an inverted signal that is inverted with respect to the original signal is fed into a second of said insulated signal conductors; and   an evaluating device connected to said insulated signal conductors, said evaluating device embodied for evaluating a level difference between the original signal and the inverted signal.   
     
     
         13 . The signal cable according to  claim 1 , wherein said shielding is embodied as a braid having individual braided strands that are mutually twisted with a varying lay length. 
     
     
         14 . The signal cable according to  claim 1 , wherein the high frequency signal cable is a balanced signal cable. 
     
     
         15 . The signal cable according to  claim 1 , wherein said mean lay length is in a range of 1 to 40 mm. 
     
     
         16 . The signal cable according to  claim 1 , wherein said lay length is in a range of up to 15 m. 
     
     
         17 . A high frequency signal cable for transmitting signals at a frequency in a GHz-range, comprising:
 insulated signal conductors being mutually twisted as a star quad to form one twisted element, said insulated signal conductors being mutually twisted with a varying lay length for reducing return losses.   
     
     
         18 . A high frequency signal coaxial cable for transmitting signals at a frequency in a GHz range, comprising:
 a signal conductor embodied as an inner conductor, said signal conductor being a stranded conductor having a plurality of individual stranded wires and said individual stranded wires being mutually twisted with a varying lay length for reducing return losses.   
     
     
         19 . A high frequency balanced signal cable for transmitting signals at a frequency in a GHz range, comprising:
 insulated signal conductors being mutually twisted in pairs or as a star quad to form a twisted element, said insulated signal conductors being stranded conductors containing a plurality of individual stranded wires and said stranded wires being mutually twisted with a varying lay length for reducing a return losses.   
     
     
         20 . A method of using a signal cable for high frequency signal transmission in a range above 100 MHz, which comprises the steps of:
 performing at least one of:
 providing a stranded conductor having a plurality of individual stranded wires for use as a signal conductor, wherein a lay length of the individual stranded wires being varied for reducing a return loss; or 
 providing a balanced signal cable having signal conductors being mutually twisted with a varying lay length for reducing return losses.